function xnsslopeFn = nsslopeFn(x)
xnsslopeFn = ((2261*sin(x(1) + x(2) + x(3)))/5000 + (1903*sin(x(1) + x(2) + x(3) - x(4)))/ ...
   5000)/((-2261*cos(x(1) + x(2) + x(3)))/5000 -  ...
  (1903*cos(x(1) + x(2) + x(3) - x(4)))/5000) ...
;